Printing and copying processes use a wide range of contacts and devices for mechanical and/or electrical connection. Printing and copying processes, such as are used in printing and copying machines, extensively employ methods and apparatus using electrical charge to perform many operations. For example, development, transfer and cleaning operations of most printing and copying machines require the transfer of electrical current, e.g., for manipulating electrostatic charge.
A part of a printing process is discussed below. A printing machine may have a photoconductive member that is electrically charged to a uniform potential and thereafter exposed to a light image of a document to be reproduced. The exposure discharges the photoconductive insulating surface of the member in exposed or background areas and creates an electrostatic latent image on the member, which corresponds to the image contained within the original document. The electrostatic latent image on the photoconductive surface is made visible by developing the image with developer powder, e.g., toner. Many development systems employ developer, which includes both charged carrier particles and charged toner particles, which adhere to the carrier particles. During development, the toner particles are attracted from the carrier particles by the charged pattern of the image areas of the photoconductive insulating area to form a powder image on the photoconductive area. The toner image may be subsequently transferred to a support surface, e.g., a sheet of paper, to which it may be permanently affixed.
A specific member, e.g., the photoconductive member discussed above, is electrically charged by transferring an electrical charge to the specific member. This transfer of charge to a member may be referred to as charging or as biasing the member. The bias of a member corresponds to the voltage applied to the member, or to the voltage potential of the member.
A sliding contact may be used as a member to bias, i.e., to transfer an electrical charge to, a rotating member, such as the photoconductive member discussed above. For example, U.S. Pat. No. 5,887,225 to Bell, the disclosure of which is incorporated herein by reference in its entirety, discloses a charge transfer device that is in electrical contact with end shafts of first and second developer rolls of a copier through a sliding electrical contact. The charge transfer device biases the rolls by transferring an electrical charge from a voltage source to the end shafts of the developer rolls via the sliding electrical contact. Other methods of transferring an electrical charge either to or from a member include placing the member to be biased in rubbing contact with a stationary brush, a flexible electrically conductive sheet, or a metal strip.
As discussed above, U.S. Pat. No. 5,887,225 to Bell discloses a charge transfer device including a sliding contact that transfers electrical charge between a voltage source and a developer roll. In Bell, the sliding contact is formed of a polymer composite of multiple electrically conductive carbon fibers. An example of a carbon fiber polymer composite is known by the trade name CarbonConX™. CarbonConX™ has a high concentration (e.g., >60% weight) of electrically conductive, high strength, continuous carbon fiber tow (or optionally metalized carbon fiber tow) compounded within a selected polymer matrix. Carbon fiber polymer composites may be used as an alternative to metal contacts in devices for electrostatic discharge applications as well as other application areas, such as sensor components, moving rotational contacts, motors, electrical switch components, etc. Applying pultrusion methods to produce the carbon fiber composites enables high strength to be obtained and allows many forms of the carbon fiber to be manufactured into various design shapes and configurations, such as, solid rods, tubes, and thin flat sheets. Moreover, the carbon fibers or metalized carbon fibers used in carbon fiber polymer composites are considered, generally, to be of high electrical conductivity as well as high strength and capable of providing statistically regular and evenly distributed electrical contact sites for charge conduction across an interface. Pultrusion methods involve, e.g., (1) pulling continuous lengths of members, such as fibers, through a host matrix material, such as a polymer, to form a composition, (2) pulling the composition through a die to shape the composition, and (3) pulling the composition through a heated region to enable the composition to cure, (e.g. cross-link) or dry.
Moreover, the carbon fibers used in carbon fiber polymer composites are considered, generally, as contact rich and capable of providing statistically regular and evenly distributed electrical contact sites. In addition, because carbon is generally non-reactive and less susceptible to corrosion when compared to other materials, such as, e.g., metal, carbon fiber may be used in harsh environments or corrosive environments, including saltwater, nuclear power environments, space, medical, and biological fields.